In daily life or work, during a point-to-point call or a conference call, when a user sometimes needs to save an important call, the user generally performs on-demand recording on an ongoing call. Generally, during a call, the user may directly press a key on an IP phone set to start recording, so that a call recording of a particular period of time can be saved.
In the prior art, using a point-to-point call as an example, a user presses a key on an internet protocol (IP) phone set during a call to start recording, and the IP phone set sends a recording request to an IP Private Branch exchange (IP PBX), that is, an IP network-based voice switch. The IP PBX creates a voice site, connects a calling party and a called party to the voice site, and sends a Session Initiation Protocol (SIP) Invite message to a SIP Server. The SIP Server selects a proper recording server from a recording server group, adds an IP address and a port number that are of the recording server to a 200 OK message, and replies to the IP PBX with the message. The IP PBX adds the recording server to the voice site, and sends a media stream of the calling party and the called party that is obtained by means of audio mixing to the recording server using the IP address and the port number that are of the recording server. The recording server acquires the media stream, thereby implementing recording.
Typically, a process from when an IP PBX creates a call to when a recording server is connected to the call involves a process of interworking and processing of multiple pieces of SIP signaling. In such period of time, the recording server cannot acquire a media stream of a user call on which audio mixing is performed. As a result, recording cannot be implemented, and the call of this period of time is lost.